1. Field of the Invention
This invention relates to spandex containing quaternary amine additives and, more specifically, to additives where quaternary amine groups are incorporated into a polyurethane oligomer or are part of a nonoligomeric structure.
2. Description of Background Art
Spandex and spandex-containing fabrics and garments are typically heat-set to provide the fiber or fabric with good dimensional stability and to shape the finished garment. Typical heat-setting temperatures used in commercial operations are 195xc2x0 C. for fabrics containing spandex and 6,6-nylon, 190xc2x0 C. when the fabric contains 6-nylon, and 180xc2x0 C. when the fabric contains cotton. It is desirable to heat-set fabrics containing cotton and spandex, but if the spandex has adequate heat-set efficiency only at temperatures used for nylon-containing fabrics, the spandex cannot be properly heat-set in cotton-containing fabrics, which will be damaged by exposure to the required high temperatures. A variety of methods have been used to improve the heat-set efficiency of spandex and thereby lower the temperature at which the spandex can be heat-set. For example, U.S. Pat. No. 5,539,037 discloses the use of low concentrations of alkali metal carboxylates and thiocyanate in spandex to increase its heat-set efficiency. However, such salts are readily dissolved during fabric processing, and their effectiveness is thereby reduced. U.S. Pat. Nos. 5,948,875 and 5,981,686 disclose the use of high proportions of 2-methyl-1,5-pentanediamine and 1,3-diaminopentane chain extender, respectively, to increase the heat-set efficiency of spandex, but making such changes to the polymer can deleteriously affect the fiber properties, and the production flexibility possible with additives is lost.
According to U.S. Pat. No. 3,294,752, quaternary amine moieties can be chemically incorporated into the segmented polyurethane chain from which spandex is made, but there is no disclosure of such incorporation on the effect, if any, on heat-set efficiency and such spandex may suffer from the same deficiency as other polymer chains so modified, namely altered fiber properties and inflexible production and spandex product lines. The use of quaternary amines as additives in spandex is unknown.
A convenient, durable, and flexible means of improving the heat-set efficiency of spandex is still needed.
The present invention is a spandex containing about 3-100 meq of quaternary amine functionality/kg of spandex wherein the quaternary amine is an additive selected from the group consisting of:
(a) oligomers comprising the reaction product of at least one diisocyanate selected from the group consisting of 1-isocyanato-4-[(4-isocyanatophenyl)methyl]benzene, 1-isocyanato-2-[(4-isocyanatophenyl)methyl]benzene, 4-methyl-1,3-phenylene diisocyanate, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-cyclohexane, 1,6-diisocyanatohexane and bis(4-isocyanatocyclohexyl)methane), and at least one quaternary amine selected from the group consisting of N,N-dialkyl-N,N-dialkanolammonium chlorides and N,N-dialkyl-N,N-dialkanolammonium alkylsulfates, wherein the alkanol grouping contains 2-4 carbon atoms;
(b) quaternary amines having the formula 
xe2x80x83wherein at least one of A, D and E is an alkyl or alkenyl group having about 10-22 carbon atoms, a mixture of such groups, or such groups including an 
moiety, B is an alkyl group having up to three carbon atoms, D is selected from the group consisting of A, linear and branched alkyl and alkenyl groups having 1-9 carbon atoms, phenyl, benzyl, and xe2x80x94(CH2CH2O)yH groups wherein y is 1-10, and Y is either chloride or alkylsulfate ion; and
(c) quaternary amines having the formula 
wherein Axe2x80x2 is an alkyl or alkenyl group having about 9-21 carbon atoms, B is an alkyl group having up to three carbon atoms, D is selected from the group consisting of A, linear and branched alkyl and alkenyl groups having 1-9 carbon atoms, phenyl, benzyl, and xe2x80x94(CH2CH2O)yH groups wherein y is 1-10, and Y is either chloride or alkylsulfate ion.
As used herein, xe2x80x9cspandexxe2x80x9d means a manufactured fiber in which the fiber-forming substance is a long-chain synthetic elastomer comprised of at least 85% by weight of a segmented polyurethane; xe2x80x9cBDMSAxe2x80x9d means N-benzyl-N,N-dimethyl-N-stearylammonium chloride; xe2x80x9cfatty acidxe2x80x9d means any of the saturated or unsaturated monocarboxylic acids, usually with an even number of carbon atoms, that occur naturally in fats and fatty oils.
It has now been found that certain quaternary amine additives in spandex result in surprising increases in the heat-set efficiency of the spandex. It is preferred that the normalized value of heat-set efficiency differences (as defined below) should be at least 0.1.
Spandex is conventionally made by first mixing a polyether, polyester, or polycarbonate glycol with a diisocyanate to form a mixture of isocyanate-terminated polymeric glycol and unreacted diisocyanate, which is also called a xe2x80x9ccapped glycolxe2x80x9d. Examples of useful polyether glycols include poly(tetramethyleneether)glycol and poly(tetramethylene-co-2-methyltetramethyleneether)glycol. Examples of useful polyester glycols include those made from the polycondensation of low molecular weight diols, for example 2,2-dimethylpropanediol, ethylene glycol, butanediol, and mixtures thereof, with dicarboxylic acids such as adipic acid and dodecanedioic acid. Useful polycarbonates include poly(pentane-1,5-carbonate)diol and poly(hexane-1,6-carbonate)diol. The most widely used diisocyanate is 1-isocyanato-4-[(4-isocyanatophenyl)methyl]benzene, but other diisocyanates such as 1-isocyanato-2-[(4-isocyanatophenyl)methyl]benzene, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, 4,4xe2x80x2-methylene-bis(cyclohexylisocyanate), and 4-methyl-1,3-phenylene diisocyanate can also be used, either alone or in mixtures. When a spandex is desired which comprises the polyurethaneurea sub-class of polyurethanes, the capped glycol is dissolved in a suitable solvent and chain-extended with a diamine to form a polymer solution. Suitable solvents include dimethylacetamide (DMAc), N-methylpyrrolidone, and dimethylformamide. Useful diamine chain extenders include ethylenediamine, 2-methyl-1,5-pentanediamine, 1,2-propanediamine, 1,3-pentanediamine, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 1,3-propanediamine and mixtures thereof. The molecular weight of the polyurethane can be controlled by the use of monofunctional chain terminators such as diethylamine.
The solution can then be dry-spun from a spinneret into a column supplied with hot gas to drive off the solvent and form the spandex, which is wound up into a package.
In one embodiment of the present invention, the spandex additives are polyurethane oligomers prepared from at least one diisocyanate selected from the group consisting of 1-isocyanato-4-[(4-isocyanatophenyl)methyl]benzene, 1-isocyanato-2-[(4-isocyanatophenyl)methyl]benzene, 4-methyl-1,3-phenylene diisocyanate, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, 1,6-diisocyanatohexane, bis(4-isocyanatocyclohexyl)-methane) and at least one quaternary amine selected from the group consisting of N,N-dialkyl-N,N-dialkanolammonium chlorides and alkylsulfates, having 2-4 carbon atoms in the alkanol portion. These oligomers can further incorporate non-quaternized amines, for example N-alkyl-N,N-diethanolamines such as N-t-butyl-N,N-diethanolamine and N-methyl-N,N-diethanolamine. Spandex containing oligomeric additives based on N-t-butyl-N-methyldiethanolammonium- and N,N-dimethyldiethanolammonium ions are preferred due to the availability of the precursor amines. Alkylsulfate counterions are preferred because they are more effective at improving heat-set efficiency.
In another embodiment, the spandex additive is a non-polymeric quaternary amine represented by the general formula I: 
wherein at least one of A, D and E is an alkyl or alkenyl group of about 10-22 carbon atoms, a mixture of such groups or such groups including an 
moiety, B is an alkyl group having up to three carbon atoms, and Y is either chloride or alkylsulfate ion, for example methylsulfate or ethylsulfate.
In a preferred embodiment,
xe2x80x9cAxe2x80x9d is (CH3)a(CH)bxe2x80x94(CH2)cxe2x80x94(CHxe2x95x90CH)dxe2x80x94(CH2)exe2x80x94Xfxe2x80x94(CH[CH3])gxe2x80x94(CH2)hxe2x80x94(N[CH2CH(OH)CH3]CH2CH2)ixe2x80x94
xe2x80x83wherein:
a is 1 or 2,
b is 0 when a is 1 and b is 1 when a is 2,
c is 5-18,
d and f are independently 0 or 1, provided that when f=1, then if the in-chain heteroatom of X is closer to the quaternary nitrogen atom than the carbonyl group, then g+hxe2x89xa72, and if the heteroatom is farther, then g+hxe2x89xa71,
e is 0-10,
g and i are 0 or 1,
h is 0-3,
the sum a+b+c+2d+e+g+h is about 10-22, and
xe2x80x9cXxe2x80x9d is selected from the group consisting of ester and amide;
xe2x80x9cBxe2x80x9d is an alkyl group of up to 3 carbon atoms;
xe2x80x9cDxe2x80x9d is selected from the group consisting of xe2x80x9cAxe2x80x9d, linear and branched alkyls and alkenyl groups having 1-9 carbon atoms, phenyl, benzyl, and xe2x80x94(CH2CH2O)yH groups wherein y is 1-10;
xe2x80x9cExe2x80x9d is selected from the group consisting of xe2x80x9cBxe2x80x9d, xe2x80x94(CH2CH2O)yH wherein y is 1-10, and 2-hydroxypropyl, and
xe2x80x9cYxe2x80x9d is alkylsulfate ion, for example methylsulfate or ethylsulfate. These ions are preferred because quaternary amines with such ions are more effective at improving heat-set efficiency.
Alternatively, formula I can be replaced by formula II, wherein B, D and Y are as above and Axe2x80x2 is an alkyl or alkenyl group having about 9-21 carbon atoms: 
For another preferred quaternary amine additive providing a spandex with higher heat-set efficiency, Formula I is as follows:
xe2x80x9cAxe2x80x9d is (CH3)xe2x80x94(CH2)cxe2x80x94(CHxe2x95x90CH)dxe2x80x94(CH2)e
wherein
c is 10-18
d and e are independently 0 or 1, and the sum c+2d+e is about 10-22,
xe2x80x9cBxe2x80x9d and xe2x80x9cExe2x80x9d are each methyl;
xe2x80x9cDxe2x80x9d is selected from the group consisting of xe2x80x9cAxe2x80x9d and linear and branched alkyl and alkenyl groups having 1-9 carbon atoms; and
xe2x80x9cYxe2x80x9d is alkylsulfate ion.
For improved solubility in DMAc, it is preferred that xe2x80x9cDxe2x80x9d be selected from linear and branched alkyl and alkenyl groups having 1-9 carbon atoms.
Yet another preferred quaternary amine additive which can provide spandex with higher heat-set efficiency is an oligomer comprising the reaction product of bis(4-isocyanatocyclohexyl)methane and at least one quaternary amine chosen from N-t-butyl-N-methyl-N,N-diethanolammonium alkylsulfate, N,N-dimethyl-N,N-diethanolammonium alkylsulfate, and mixtures thereof and, optionally, N-t-butyldiethanolamine.
The quaternary amine additives are effective at improving heat-set efficiency in spandex prepared from, for example, poly(tetramethylene-co-2-methyltetramethyleneether)glycol, 1-isocyanato-4-[(4-isocyanatophenyl)methyl]benzene, and ethylenediamine but somewhat less effective when incorporated into spandex which already has a high heat-set efficiency, for example spandex prepared from poly(tetramethyleneether)glycol, 1-isocyanato-4-[(4-isocyanatophenyl)methyl]benzene, ethylenediamine, and 2-methyl-1,5-pentanediamine, especially at high heat-set temperatures (for example, in excess of about 185xc2x0 C.).
The quaternary amine additives can usually be dissolved in the spinning solvent and the resulting solution added to the polymer spinning solution. When other additives such as stabilizers and pigments which require milling are also to be added, a slurry masterbatch comprising the quaternary amine, the other additives, spinning solvent and optionally polyurethane (for viscosity optimization) and a dispersant can be milled and then mixed into the spinning solution.
The quaternary amine additives are used at levels of about 3-100 meq of quaternary amine per kg of spandex. The more effective quaternary amines can be used at levels of about 5-35 meq/kg of spandex.
Quaternary amines useful in the present invention include the following: 
hydrogenated tallow(2-ethylhexyl)dimethylammonium methosulfate (Arquad HTL8-MS-85), 
N,N-bis(hydroxyocta[ethyleneether)-N-methyl-N-talloyl-ammonium methylsulfate (Avitex DN-100), 
N-benzyl-N,N-dimethyl-N-stearylammonium chloride (xe2x80x9cBDMSAxe2x80x9d), 
N,N-bis(hydroxyocta[ethyleneether)-N-methyl-N-octadecylammonium methylsulfate, 
di-(nortallowcarboxyethyl)hydroxyethylmethylammonium methosulfate (Varisoft WE-16), 
N,Nxe2x80x2-bis(2-hydroxypropyl)-N,Nxe2x80x2-bis(2-talloylpropyl)-Nxe2x80x2-methyl-1-amino-2-ammonioethane methylsulfate (Avitex ML), 
N-(3-isostearylamidopropyl)-N,N-dimethyl-N-ethylammonium ethyl sulfate (Schercoquat IAS), 
2-isoheptadecyl-1-hydroxyethyl-1-ethyl-imidazolinium ethyl sulfate (Schercoquat IIS), 
methyl-1-oleyl-amidoethyl-2-oleyl-imidazolinium methyl sulfate (Varisoft 3690), 
methyl bis(hydrogenated tallow amidoethyl)-2-hydroxyethyl ammonium methyl sulfate (Varisoft 110-75), 
methyl bis(oleylamidoethyl) 2-hydroxyethyl-ammonium methyl sulfate (Varisoft 222-LT), 
distearyldimethylammonium methosulfate (Sumquat 6045), 
methyl-1-hydrogenated tallow amidoethyl-2-hydrogenated tallow imidazolinium methyl sulfate (Varisoft 445), 
1-octadecyltrimethylammonium methylsulfate, 
1-tridecyltrimethylammonium sulfate, and 
N-benzyl-N,N-dimethyl-N-1-octadecylammonium methylsulfate. Arquad(copyright) HTL8-MS-85 is a product of Akzo. Avitex(copyright) ML and Avitex(copyright) DN-100 are registered trademarks of E. I. du Pont de Nemours and Company. Rewoquat(copyright) WE 38 DPG is a product of Witco Corp. Schercoquat(copyright) IAS and Schercoquat(copyright) IIS are products of Scher Chemical Company. Sumquat(copyright) 6045 is a product of Zeeland Chemical. Varisoft(copyright) 3690, Varisoft(copyright) 110-75, Varisoft(copyright) 222-LT-90, Varisoft(copyright) 445 and Varisoft(copyright) WE16 are products of Witco Corp. N-Benzyl-N,N-dimethyl-N-stearylammonium chloride (xe2x80x9cBDMSAxe2x80x9d) is a product of Aldrich Chemical Company.
Many of the commercially available quaternary amines useful in the spandex of this invention can be derived in a series of steps from naturally occurring mixtures of fatty acids, for example, by amination to an amide, dehydration to a nitrile, reduction to an alkylamine, and finally alkylation to the quaternary amine. The structures shown above are believed to be typical of, and/or the predominant species in, the commercial products.
Various additives useful in the present invention were prepared as follows.